Circuit breaker

ABSTRACT

A high performance, manually and automatically operable, trip-free magnetic circuit breaker incorporates novel means for mounting and coupling circuit breaker units to achieve multipole operation. An actuator in each pole has a shaft extending through a housing wall and fitting in splined engagement with the shaft of a corresponding actuator in an adjacent pole mounting the actuators for unison pivotal movement between a position where one of the actuators is engaged and pivoted by movement of the beaker contacts to an open circuit position in one pole for pivoting the other actuator to trip the breaker components in the adjacent pole to open the circuit in the adjacent pole. A tie-pin having a peripheral groove therein is snugly fitted into openings in the operating handles of the breaker pols and has coil springs fitted over the pin between pairs of the handles, one spring having a convolution of reduced diameter fitted into the pin groove for retaining the pin in the handle openings.

Conventional high performance, manually and automatically operable,trip-free magnetic circuit breakers have been adaptable for use inseries, shunt and relay trip application, for instantaneous or timedelayed trip operation, for use as "flux switch" type circuit breakerswhere high transient currents in the breaker circuit have beenanticipated, for use with auxiliary switches, and for use in multipoleapplications. However, such adaptability has been achieved only bysubstituting a substantial number of breaker components in adapting thebreakers for each type of breaker operation. As a result, circuitbreaker costs have been high due in part to the high unit cost ofbreaker components resulting from the need for many different tools andresulting from the small manufacturing volumes of some of the specialbreaker components. Breaker costs have also been increased by the needfor maintaining a large inventory of many different breaker parts.

Most important, such conventional circuit breakers have requiredperformance of a large number of critical hand operations during breakerassembly and calibration. These assembly operations have beentime-consuming and expensive, have imposed excessive delay betweencustomer order and delivery, have required the employment of skilledassembly personnel, have resulted in high rejection rates duringassembly, have frequently prevented salvaging of components fromimproperly assembled breakers, and have resulted in the manufacture ofbreakers which have not displayed consistent performancecharacteristics.

For example, such known circuit breakers have frequently requiredwelding of pigtails to movable contact arms, have utilized magnetic coremeans which have been soldered or cold-headed to the magnetic framewhich supports the magnetic actuating coils in the breakers to obtainsecure mounting of the core means relative to the coil means; and haverequired bending of latch components, clappers and the like at assemblyto obtain proper interaction of breaker linkage systems with otherbreaker components. In some of the previously known circuit breakers,the collapsible linkages which have been used have required excessiveriveting and in most such circuit breakers, breaker housing sectionshave been riveted together after breaker assembly and calibration hasbeen completed.

Each of these assembly operations used in manufacturing the conventionalcircuit breakers has tended to impose cost and performance penalties.Thus, the critical hand assembly operations have been slow and expensiveto perform as will be understood. They have also resulted in assemblyerrors which have seriously reduced manufacturing yields. Welding andsoldering tend to introduce splatter which can result in immediatebreaker failure or which can result in failure of the breakers duringsubsequent use. Welding, soldering, cold-heading and bending also tendto destroy corrosion-preventing coatings provided on some breakercomponents. These assembly operations also introduce material stressessuch as work-hardening which are deleterious to breaker performance. Forexample, welding of pigtails can result in stiff pigtail movement whichprevents smooth movement of the contact arm during breaker operation.The cold-heading of a magnetic core means in mounting the core means ona coil-supporting frame introduces work-hardening which can result inthe build-up of residual magnetism in the cold-headed components duringsubsequent use of the circuit breaker. Riveting of the components of acollapsible linkage risks tight operation of the linkage which canretard proper opening of the circuit breaker. Riveting of the casingalso tends to result in cracking of dielectric casing parts. Further,where such welding, soldering, cold-heading or riveting result in errorsof assembly, salvaging of the welded, soldered, cold-headed or rivetedparts is usually difficult and expensive.

In addition, some previously known circuit breakers have been subject tovarious structural deficiences which have reduced the convenience oreffectiveness of their performance. For example, where the housings ofsuch breakers have been riveted together, the rivets have sometimescontributed to arcing or shorting outside the breaker housingsparticularly where high overload current conditions have occurred inmultipole breaker applications. In most such known breakers thecollapsible linkages have been subjected to heavy loads so that all ofthe linkage elements have been made of metal. In such linkages, evenslight corrosion of the metal elements in metal-to-metal pressureengagement can result in retardation of linkage movement and suchbreakers have sometimes required lubrication when used in hostileenvironments. In other known breakers, where a clapper is adapted to bedrawn into engagement with a magnet pole face and to strike a breakertripping element during such movement, it has been difficult toprecisely position the clapper to assure proper tripping. That is, ifthe clapper engages the tripping element too far away from the poleface, the clapper force may be too small to initiate tripping. On theother hand if the clapper strikes the tripping element too close to thepole face, the extent of the resulting movement of the tripping elementmay be insufficient to effect tripping.

In some previously known circuit breakers, calibration of the breakerunits has been accomplished from the side of the breaker. Accordingly,when a group of such units is used in a multipole breaker application,the calibration had to be completed before assembly of the units in thedesired multipole arrangement. However, because the individual breakerunits have been subject to a different magnetic environment in themultipole arrangement, such calibration prior to a final assembly hasnot always been fully effective. Further, the prior art techniques usedfor coupling breaker handles and the like in multipole applications havetended to be somewhat inconvenient to use. In addition, where previouslyknown breakers have been used with auxiliary switches, the additionalforces required for operation of the auxiliary switches have sometimesmade it difficult to properly calibrate the breakers or to obtainuniform and reliable breaker performance. Similarly, where the prior artbreakers have been adapted for flux switch operation, the breakers havebeen difficult to calibrate and have not always been adapted towithstand suitably high transient currents without nuisance tripping.

It is an object of this invention to provide a novel and improved, highperformance, manually and automatically operable, trip-free magneticcircuit breaker; to provide such a circuit breaker which is of compact,rugged and inexpensive construction; to provide such a breaker which isreadily adaptable at low cost for use in wide variety of circuit breakerapplications; to provide such a circuit breaker which is easily andrapidly assembled; to provide such a breaker which is adapted to beassembled without requiring hand adjustments during such assembly; toprovide such circuit breakers which display consistent performancecharacteristics; to provide such circuit breakers which are of compactconstruction and small size but which display improved rupture capacity;to provide such circuit breakers which are adapted to be easily,accurately and conveniently calibrated; to provide such circuit breakerswhich are easily and accurately calibrated after assembly in a multipolecircuit breaker arrangement; to provide such circuit breakers which areadapted to withstand substantial wear over a long service life; toprovide such circuit breakers which display improved resistance tocorrosion and which are significantly less subject to jamming as aresult of corrosion; to provide such circuit breakers which are operablein hostile environments without requiring lubrication; to provide suchcircuit breakers in which build-up of residual magnetism does not tendto occur; to provide such circuit breakers from which breaker componentsare eaily salvaged at any time; to provide such circuit breakers whichdo not require extensive riveting during assembly; to provide suchcircuit breakers which are adapted to be manufactured with highmanufacturing yields; to provide such circuit breakers which are easilymounted on control panels; to provide such circuit breakers which areeasily calibrated after adaptation for auxiliary switch application; toprovide such circuit breakers which are conveniently coupled togetherfor multipole operation; and to provide such circuit breakers which areeasily calibrated and which display reduced nuisance tripping whenadapted for flux type circuit breaker application.

Briefly described, the circuit breaker of this invention comprises apair of dielectric casing sections fitted together to form a housinghaving terminal openings between the sections at one end of the housing.Abutments are provided on the exterior surfaces of the casing sectionsadjacent the openings, and terminals which are disposed in the openingshave tabs deformed around the abutments for holding the casing sectionstogether at that end of the housing. Mounting and cam surfaces are alsoprovided on the exterior surfaces of the casing sections at the cornersof the opposite end of the housing. Metal clips fit over these exteriorcasing surfaces, the clips having cam surfaces engaged with the camsurfaces on the casing sections for holding the casing sections togetherwith a precisely perdetermined force. The clips have detent means whichposition the clips until circuit breaker assembly have been tested andhave tabs which are deformed after testing for locking the clipspermanently in place. The clips are provided with tapped mounting holes.In this arrangement, the housing is easily and accurately assembledwithout risk of cracking the dielectric casing sections; the housing isfree of rivets which might reduce electrical clearances in the breaker;if dissassembly is required, the casing sections and clips are fullyreuseable; and the housing is adapted for conveniently mounting on acontrol panel without requiring mounting inserts in the housing.

The circuit breaker also includes an improved contact system in which apair of first contacts are mounted in spaced relation in the housing andin which a movable contact arm is pivotally mounted on the housing formoving a bifurcated end of the arm into and out of bridging engagementwith the first contacts for opening and closing the breaker circuit. Themovable contact arm is normally biased to open circuit position. In thisarrangment, no pigtails need be welded to the movable contact arm; adouble contact break is obtained; and the arrangment of the contact armis adapted to achieve improved blow out of arcs formed during opening ofthe breaker circuit. Thus the current breaker achieves more consistentperformance, longer service life and improved rupture capacity.

The circuit breaker also includes an improved collapsible linkage forpermitting opening and closing of the breaker circuit in response tomanual movement of an operating handle and for permitting automaticopening of the breaker circuit when the linkage is tripped on theoccurrence of an overload current in the circuit. In the linkage, afirst link has one end pivotally connected to the operating handle andhas a first latch which is engaged with the contact arm and which ispivotally mounted at the opposite end of the first link for movementbetween latching and unlatching positions. The first latch has a camsurface to be engaged for manually holding the first latch in itslatching position. A second link having a cam follower is pivotallymounted on the first link for movement between a first position engagingthe cam follower with the cam surface of the first latch for holding thefirst latch in its latching position and a second position in which thecam follower is disengaged from the first latch. A second latch, alsopivotally mounted on the first link, is movable from a latching positionholding the second link in its first position to an unlatching positionin which the second link is permitted to move to its second position. Atripping member also pivotally mounted on the first link normally holdsthe second latch in its latching position but is trippable by an appliedforce for releasing the second latch for movement to its unlatchingposition. When the first and second latches are in the latchingpositions as described, movement of the operating handle between twocircuit positions is effective to move the linkage through an overcenterposition against the bias on the movable contact arm, thereby to holdthe arm securely in closed position or to permit the arm to move sharplyto open circuit position. Tripping of the tripping member by an appliedforce on the occurrence of an overload current in the breaker circuit isalso effective to collapse the linkage for permitting the contact arm tomove sharply to open circuit position independently of the position ofthe operating handle.

In the dual latch linkage system of this invention, the links, latchesand tripping member are arranged to provide cumulative mechanicaladvantage such that, although the movable contact arm is normally heldin closed circuit position with substantial force, the tripping memberis adapted to retain the second latch in its latching position with amuch smaller force. Preferably also the tripping member is formed ofprecision molded plastic lubricity material. In this arrangement, only arelatively light force need be applied to the tripping member forinitiating automatic circuit-opening operation of the circuit breaker.Further, although the plastic tripping member is adapted to withstandthe light forces applied to it without cold flow or excessive wear, thetripping member is formed with such precision that the linkage isadapted to be easily and accurately assembled inside the circuit breakerand does not require cutting, trimming or bending or the like duringfinal circuit breaker assembly. In addition, the plastic tripping memberis not subject to corrosion even in hostile environments and there is nometal-to-metal pressure contact between the plastic tripper and thesecond latch. Accordingly, the linkage provides smooth and consistentcircuit breaker performance and does not require lubrication atassembly.

The circuit breaker of this invention also includes a clapper which ismagnetically movable from a rest position to an actuating position fortripping the tripping member of the collapsible linkage as abovedescribed, a magnetic frame supporting a magnetic coil to be responsiveto current conditions in the breaker circuit, and magnetic core meansfitted within the coil to cooperate with the frame in defining amagnetic circuit for moving the clapper to its actuating position in theoccurrence of an overcurrent condition on the breaker circuit. The frameengages abutments formed on the inner surfaces of the casing sections ofthe housing for mounting and precisely locating the frame within thehousing chamber; the coil is wound on a hollow spool mounted on theframe, the spool having resilient fingers positioned at one end of thespool; the core has a flange at one end engaged with additionalabutments on the casing sections for mounting and precisely locating thecore in the chamber while permitting the core to extend into the coil tobe precisely located relative to the coil by engagement with theresilient fingers on the coil spool; and the clapper engages otherabutments on the casing for mounting and precisely locating the clapperfor pivotal movement relative to the core and frame within the housingchamber. Preferably, the clapper engages additional abutment means onthe inner surface of the casing section for properly positioning theclapper in its rest position in the chamber. Preferably also the portionof the operating handle pivotally connected to the collapsible linkageengages other abutments on the inner surface of the casing sections. Inthis arrangement, where the operating handle and the various magneticcomponents of the circuit breaker are all located by abutments providedon the same precision molded casing sections, the components are easilyand accurately located in the breaker relative to each other and to thetripping member of the collapsible linkage. The magnetic components areaccurately located without requiring cutting, bending or trimming duringfinal circuit breaker assembly and without requiring soldering or coldheading or the like such as might introduce work hardening or otherundesired material stresses. The magnetic components are also easilydisassembled for salvaging or the like free of damage to any of thecomponents whenever such disassembly is desired.

The circuit breaker also includes an improved calibration system inwhich a calibrating member has a first portion rotatably mounted in thehousing wall adjacent the operating handle and has a second threadedportion extending into the housing chamber to be rotatable with thefirst portion. A tension coil spring has a convolution at one end fittedin threaded engagement with the threaded portion of the calibratingmember and has its opposite end connected to the clapper for biasing theclapper to its rest position, whereby the spring applies a selectedforce to the clapper in a selected direction but is movable in responseto rotation of the calibrating member for threadedly advancing said oneend of the spring on the calibrating member. In this way, the springapplies substantially the same spring force to the clapper but appliedthat force in a different direction so that the spring force has adifferent moment arm relative to the clapper pivot for calibrating thecircuit breaker. In this arrangement, substantial rotation of thecalibrating member produces small variation of the bias on the clapperto achieve high resolution in calibration of the breaker. Thecalibration system is also compact and inexpensive and is located at theoperating handle end of the breaker to be readily accessible even whenseveral of the circuit breakers are mounted together in a multipolecircuit breaker application. The calibrating member is alsosubstantially free of springback for assuring accurate calibration; thespring is not subjected to greatly varying stresses during use andtherefore provides consistent performance at various calibrations over along service life; and where initial tension is provided in a springwith a low spring rate as is preferred, the spring provides the desiredtorque in a compact spring configuration while assuring that the torquedoes not increase significantly as the clapper is moved between its restand actuating position, thereby resulting in a snappier clapper action.

The circuit breaker also includes an improved auxiliary switchmechanism; an improved flux member for use in adapting the breaker forflux type circuit breaker application; an improved multipole actuatorsystem for tripping all of the circuit breakers in a multipole breakerwhen one of the poles has been tripped; an improved system for gangingoperating handles of the circuit breaker units in a multipole circuitbreaker; alternate terminals for use in adapting the circuit breaker forseries, shunt or relay type applications; and a modular constructionwhich permit convenient adaption of the breaker for use in a variety ofdifferent types of circuit breaker applications.

Other objects, advantages and details of the circuit breaker of thisinvention appear in the following detailed description of preferredembodiments of the invention, the detailed description referring to thedrawings in which:

FIG. 1 is a side elevation view of a shunt trip embodiment of thecircuit breaker of this invention;

FIG. 2 is one end elevation view of the circuit breaker of FIG. 1;

FIG. 3 is an opposite end elevation view of the circuit breaker of FIG.1;

FIG. 4 is a top elevation view of the circuit breaker of FIG. 1;

FIG. 5 is a bottom elevation view of the circuit breaker of FIG. 1;

FIG. 6 is a partial side elevation view of the circuit breaker of FIG. 1illustrating assembly of the mounting clip thereon;

FIG. 7 is a section view along line 7-7 of FIG. 4 with the movableswitch components removed illustrating the construction of one of thecasing sections of the circuit breaker of FIG. 1;

FIG. 8 is a section view similar to FIG. 7 showing the movable circuitbreaker components mounted in the casing section of FIG. 7 with circuitthe breaker in closed circuit position;

FIG. 9 is a section view similar to FIG. 8 showing the movable circuitbreaker components in section;

FIG. 10 is a section view similar to FIG. 8 showing the movable circuitbreaker components in open circuit position after manual opening of thebreaker circuit;

FIG. 11 is a section view similar to FIG. 8 showing the movable circuitbreaker components as the circuit breaker is inititing movement to opencircuit position on the occurrence of an overload in the breakercircuit;

FIG. 12 is a partial section view along line 12--12 of FIG. 3;

FIG. 13 is a partial section view along line 13--13 of FIG. 8;

FIG. 14 is a partial side elevation view similar to FIG. 8 illustratingtripping motion of the circuit breaker of Fig. 1 in response to anoverload condition in the breaker circuit;

FIG. 15 is a partial side elevation view similar to FIG. 14 illustratinga subsequent stage in the tripping motion of the circuit breaker of FIG.1 in response to an overload condition of the breaker circuit;

FIG. 16 is a partial section view similar to FIG. 8 illustrating anembodiment of the circuit breaker of FIG. 1 adapted for relay tripoperation;

FIG. 17 is a partial section view similar to FIG. 8 illustrating anembodiment of the circuit breaker of FIG. 1 adapted for series-tripoperation;

FIG. 18 is a partial section view similar to FIG. 8 illustrating anembodiment of the circuit breaker of FIG. 1 adapted for operation withan auxiliary switch illustrating the circuit breaker in open circuitposition;

FIG. 19 is a partial section view similar to FIG. 18 illustrating thecircuit breaker with an auxiliary switch and with the circuit breaker inclosed circuit position;

FIG. 20 is a section view along line 20--20 of FIG. 18;

FIG. 21 is a partial elevation view similar to FIG. 8 illustrating anembodiment of the circuit breaker of FIG. 1 adapted for "flux-switch"type circuit breaker operation;

FIG. 22 is a top elevation view similar to FIG. 4 illustrating amultipole circuit breaker of this invention;

FIG. 23 is a section view along line 23--23 of FIG. 22;

FIG. 24 is a partial section view along line 24-24 of FIG. 22illustrating the multipole circuit breaker of this invention in closedcircuit position;

FIG. 25 is a section view similar to FIG. 24 illustrating movement ofvarious multipole actuators in response to opening of one pole of themulipole circuit breaker on occurrence of an overload condition in thatpole of the circuit breaker; and FIG. 26 is a partial section view alongline 26--26 of FIG. 25.

Referring to the drawings, 10 in FIGS. 1-15 indicates a preferredembodiment of the novel and improved circuit breaker of this inventionwhich provides for manual opening and closing of a circuit and forautomatic, trip-free operation in response to the occurrence of anoverload current or voltage in the circuit and which, in the embodimentillustrated in FIGS. 1-15, is adapted for shunt-trip type of circuitbreaker application. As illustrated, the circuit breaker 10 is shown toinclude a housing indicated generally at 12, an operating handle 14, acontact system indicated generally at 16 (see FIGS. 8-13), a collapsiblelinkage 18 (see FIGS. 8-11), a magnetic actuation system indicatedgenerally at 20 (see FIGS. 8-11, 14 and 15), and a calibration systemindicated generally at 22 (see FIGS. 4 and 8-11).

The base or housing 12 embodies a pair of casing or housing sections 24and 26 of a rigid dielectric material such as thermoplastic polyester,phenolic resin, glass-filled nylon or the like which are preferablyformed in precision molding processes or the like so that each casingsection has a plurality of structural features precisely locatedrelative to each other on the section at very low cost. Preferably, thecasing section 24 has a generally flat principal wall 24.1 and has edgewalls 24.2, 24.3, 24.4 and 24.5 upstanding from the principal wall. SeeFIG. 7. The casing section 26 is of generally similar configuration, theedge walls of the two casing sections being fitted together to define ahousing chamber 28 as shown in FIGS. 7-11. Preferably located surfacessuch as those formed by upstanding abutments 24.6 and bosses 24.7 areprovided on the edge walls of the casing section 24 (see FIG. 7) whilecorresponding locating surfaces in the form of interfitting abutmentsand recesses are provided on the edge walls of the casing section 26 forpermitting the casing sections to be easily and accurately fittedtogether. The edge walls of the casing sections also have recesses,notches or slots which cooperate when the sections are fitted togetherto define a plurality of openings extending into the housing chamber 28,these openings including terminal openings 30 and 32 at one end of thehousing 12, a bottom opening 38 at that end of the housing, an opening34 for the operating handle 14 at the opposite end of the housing 12 andan opening 36 for the calibration system 22 adjacent to the operatinghandle opening at said opposite housing end. Preferably such slots andthe like in the edge walls of the casing sections also cooperate to forman arc vent opening 40 (see FIG. 3) and test openings 42 (see FIG. 2) inthe housing as is discussed further below.

In accordance with this invention the exterior surfaces of the casingsections have a plurality of mounting surfaces and the like integrallyformed on the casing sections and precisely located relative to eachother on the casing exterior for use in achieving convenient, accurateand high-yield assembly of the housing 12. That is, each corner area ofthe casing section 24 to be disposed at the operating handle end of thehousing 12 has a recess configuration 44 on its exterior surfacedefining a clamping cam surface 44.1 (see FIG. 4) and a clearance recess44.2 on the edge wall 24.2, defining a guide cam surface 44.3 and alocking slot 44.4 on the principal wall 24.1, and defining a slot 44.5to form a detent abutment 44.6 on a lateral edge wall 24.4 or 24.5. Theclamping cam surface 44.1 is spaced a selected precise distance fromlocating surfaces on the edge wall 24.2 of the casing section, and theguide cam surface 44.3 has a slight downward tilt or incline as viewedin FIG. 6. Corresponding corner areas of the casing section 26 havecorresponding recess configurations 44.

A metal mounting clip 46 or the like is then fitted within a pair ofrecess configurations 44 formed on the respective casing sections 24 and26, the clip being provided with various structural features whichcooperate with the mounting surfaces and the like formed by the recessconfigurations on the casing sections to hold the casing sectionstogether, temporarily or permanently, to form the housing 12. That is,the clip 46 includes a top sheet portion 46.1 having a cam slot 46.2which, as shown in FIG. 4 engages the clamping cam surfaces 44.1 on thecasing sections 24 and 26 for holding the sections together. As the camslot 46.2 is shallow and is formed in a sheet portion of the clip, theedges of the cam slot are adapted to be precisely formed by a simpleblanking operation and are therefore adapted to hold the casing sectionssecurely together with a precisely predetermined force without risk ofcracking the dielectric casing section materials. An apertured detentclip portion 46.3 disposed in a plane perpendicular to the top clipportion 46.1, and two guide clip portions 46.4 disposed in planesperpendicular to the top and detent portions of the clip, then cooperatewith surfaces on the casing sections to properly position and hold theclip on the casing sections, the guide portions of the clip having tangs46.5 which engage respective inclined guide cam surfaces 44.3 on thecasing sections as the clip 46 is fitted over the corner areas of thehousing for applying stress to the clip guide portions as the apertureddetent portion of the clip is snapped over the detent abutments 44.6 onthe casing sections, thereby to temporarily hold the clip on the casingsections with the clamping cam surfaces of the clip and casing sectionsproperly engaged. Such temporary mounting of the clip permits thecircuit breakers to be tested after assembly without need for othertemporary holding means for the housing sections. The metal clips 46 fitsnugly into the recess configurations in the casing section to be flushwith the exterior section surfaces outside the recess configurations toachieve a compact housing structure. However, because the casingsections are held together by the clamping cam surfaces, the fit of theclip guide portions against the principal walls of the casing sectionsis not relied upon for holding the sections together. That is, if theclip guide portions display any resilience, the securing of the casingsections together is not affected by such resilience. Each guide portionof the clip 46 has a locking tab 46.6 which is deformed into acorresponding locking slot 44.4 in a casing section after testing of thebreaker and after it has been established that the circuit breaker 10has been properly assembled, thereby to lock the mounting clips more orless permanently in place on the casing sections. However, as it is thefitting of the tabs 46.6 into the locking slots which secures the clipsin place rather than any clamping of the casing sections by the deformedtabs, there is no risk of cracking the casing materials duringdeformation of the tabs. Of course, if desired, the tabs 46.6 areadapted to be redeformed out of the locking slots if disassembly of thecircuit breaker should ever be desired, thereby to permit suchdisassembly without risk of damage to the casing sections. Each mountingclip 46 also has a tapped or threaded hole 46.7 therein aligned with theclearance recesses 44.2 formed in the casing sections, whereby mountingscrews are adapted to be engaged with the clip for mounting the circuitbreaker 10 on a control panel or the like where desired.

Preferably, abutments 48 are also formed on the exterior surfaces of thecasing sections 24 and 26 adjacent each of the terminal openings 30 and32, and preferably adjacent each side of the bottom opening 38, at theother end of the housing 12. Breaker terminals 50 and 51 fitted into theopenings 30 and 32 are then provided with tabs 50.1 and 51.1 which aredeformed around pairs of the exterior casing abutments 48 adjacent theterminal openings after final breaker assembly for securely locking thecasing sections together at that end of the housing as shown in FIG. 5.Where the circuit breaker 10 is adapted for shunt-trip type of circuitbreaker operation as shown, an additional terminal 52 is extendedthrough the bottom opening 38 in the housing 12 and tabs 52.1 on thatterminal are deformed around a pair of the abutments 48 adjacent theopening 38.

In accordance with this invention, the casing sections 24 and 26 arealso provided with a plurality of integral mounting surfaces, abutmentsand the like on the interior surfaces of the casing sections, wherebythese interior casing features are also precisely located relative toeach other in an inexpensive way for use in precisely locating variouscircuit breaker components relative to each other within the housingchamber 28. In the casing section 24 for example, such interior casingfeatures (which are each discussed further below) include a recess 54for use in pivotally mounting the operating handle 14 on the housing 12,a recess 54.1 forming a stop for a biasing spring for the operatinghandle, a recess 56 forming an abutment for locating an arc chute memberin the chamber 28, a recess 58 forming abutments for locating a magneticframe member in the chamber 28, a recess 60 and a recess 60.1 formingabutments for locating magnetic core means in the circuit breaker,abutments 62, 62.1 and 62.2 for use in locating a magnetic clapper inthe chamber 28, a slot-shaped recess 64 for use in locating a cover overthe bottom opening 38 in the housing, and recesses 66 and 66.1 for usein locating the calibration system 22 in the chamber 28. The casingsection 26 has corresponding recess and abutment features formed on itsinterior surfaces for cooperating with the noted interior features ofthe casing section 24 in locating various circuit breaker components inthe chamber 28.

In the circuit breaker 10 of this invention, a frame 68 of amagnetically permeable metal material such as annealed steel is mountedin a central position in the housing chamber 28 as shown in FIG. 8. Theframe has a central frame portion 68.1, has a pole face 68.2 extendingfrom one end of the central frame portion, has a clearance slot 68.3extending through the pole face 68.2 into the central frame portion, hasa coil support arm 68.4 apertured at 68.5 (see FIG. 9) extending in onedirection from the opposite end of the central frame portion, and has apair of integral wings 68.6 extending in an opposite direction from saidopposite end of the central frame portion in spaced juxtaposed relationto each other, the wings having respective, aligned pivot pin holes 68.7therein. The frame 68 is mounted and precisely positioned in the housingchamber 28 by fitting one side of the frame in the recess 58 in thecasing section 24 and by fitting the opposite side of the frame in acorresponding recess in the casing section 26, whereby the pole face68.2 and the pivot pin holes 68.7 of the frame are precisely located inthe chamber 28.

In the contact system 16 of the circuit breaker 10, an arc chute member70 of a rigid dielectric material such as phenolic resin, glass-filledthermoplastic polyester or the like has a bottom wall 70.1, has an endwall 70.2, and has a pair of sloped outer side walls 70.3 and 70.4spaced at either side of a similarly sloped central dividing wall 70.5for forming contact chambers 70.6 and 70.7 at respective opposite sidesof the dividing wall. See FIGS. 12 and 13. The outer side wall 70.3 andthe dividing wall 70.5 have corresponding grooves 70.8 receiving theedges of one end of the breaker terminal 52 therein for mounting a firstfixed contact 72 secured to the terminal 52 within the contact chamber70.6. The bottom wall 70.1 of the arc chute member has a recess 70.9therein and is open adjacent the end wall 70.2 for receiving one end ofthe breaker terminal 50 therein, thereby to mount a second fixed contact74 attached to the terminal 50 within the contact chamber 70.7. The arcchute member 70 is mounted in the recess 56 in the casing section 24,and in a corresponding recess in the casing section 26 while theopposite ends of the terminals 50 and 50 are extended from the housingchamber 28 through openings 30 and 38 respectively in the housing 12.The terminal 51 is similarly mounted between the casing sections toextend from the housing chamber through the opening 32 in the housing.The end wall 70.2 of the arc chute member has a gridded aperture formedtherein as best seen in FIG. 3, whereby the gridded aperture is alignedwith the opening 40 in the housing so that the contact chambers 70.6 and70.7 are each separately vented outside the circuit breaker housing 12.When a magnetic actuation coil 75, to be discussed further below, ismounted on the coil support arm 68.4 of the frame member, one end 75.2of the coil is electrically connected to the line terminal 51 while theopposite end 75.2 of the coil is electrically connected to theshunt-trip terminal 52 as shown in FIG. 8.

In the contact system 16 of the circuit breaker 10, a second contactmeans, preferably a movable contact arm 76 of an electrically conductivemetal material such as copper or brass, is also mounted for pivotalmovement on the frame member 68. The contact arm has one end bifurcatedas indicated at 76.1 and 76.2 (see FIG. 12), has a pair of spaced,integral, juxtaposed wings 76.3 at its opposite end fitted between thewings 68.6 of the frame member, and has an intermediate arm portion 76.4which electrically connects the bifurcated arm ends to each other. Apair of electrical contacts 78 and 80 are mounted on the respectivebifurcations 76.1 and 76.2, these bifuracted arm ends preferably beingstepped as shown so that the intermediate arm portion 76.4 electricallyconnecting the bifurcations is disposed in substantially the same planeas the outer surfaces of the contacts 78 and 80. The wings 76.3 of themovable contact arm have respective aligned slots 76.5 therein, haverespective aligned pivot pin holes 76.6, and each preferably have a tab76.7 struck therefrom to extend toward the other wing of the contactarm. A pivot pin 82 extends through the contact arm slots 76.5 andthrough pivot pin holes 68.7 in the frame and the ends of the pin arepositioned closely adjacent the principal walls of the casing sections24 and 26 to assure retention of the pin in the slots 76.5 and holes68.7. A double section coil spring fitted over the pin 82 has a centralbight 84.1 bearing against the frame 68 and has its opposite ends 84.2fitted under respective tabs 76.7 on the movable contact arm, thereby tobias the arm for pivotal movement in a clockwise direction as viewed inFIGS. 8 and 9. A pair of coiled torsion springs (right and left) couldalso be used.

In this arrangement, the contact arm 76 is pivotally mounted on theframe 68 for moving the bifurcated end of the contact arm toward or awayfrom the plane occupied by the fixed contacts 72 and 74, whereby thecontacts 78 and 80 are engaged with or disengaged from the respectivefixed contacts 72 and 74. In this way, the contact arm is adapted toclose a circuit between the fixed contacts 72 and 74 by bridging thefixed contacts. However, the arm is normally biased by the spring 84 toopen that bridging circuit. Because a bridging circuit is adapted to beclosed by pivoting of the contact arm 76, the convenience and desirablecontact closing forces obtained with a pivotal contact arm are achievedbut no flexible pigtail or the like such as might tend to retard smoothpivoting of the contact arm, or which might be subject to fatigue duringuse, need be attached to the movable arm. Further the use of thebridging contact arm 76 provides a double contact make and break inclosing and opening the noted circuit, thereby permitting the contactsystem 16 to function with greater speed and with less arc erosiondamage to the breaker contacts and to provide the breaker 10 withgreater rupture capacity. The bifurcated ends 76.1 and 76.2 of thecontact arm fit into respective contact chambers 70.6 and 70.7 so thatthe mating pairs of contact 72-78 and 74-80 are separated by thedividing wall 70.5 as the mating contact pairs are engaged anddisengaged. In this way the fixed contacts 72 and 74 are adapted to bespaced closed together without risk of arcing therebetween and eachmating contact pair is shielded from arc erosion splatter or the likeoriginating at the other mating contact pair. Further, with thisarrangement of the contact system 16, magnetic fields are formed bycurrent flow in the terminals 50 and 52 and in the contact arm 76 duringopening of the breaker circuit such that arcs formed between the matingcontact pairs tend to remain separate and tend to be deflected indirections away from the contact arm to be vented from the contactchambers 70.6 and 70.7 through the housing vent opening 40 and to beextinguished in passing through the gridded aperture in the arc chuteend wall 70.2. In this way, the single, one piece arc chute 70 handlesall arcing problems and also facilitates contact mounting. Desirably, acover member 79 of a stiff fiberboard material or the like, apertured topass the terminal 52 therethrough, is mounted over the bottom opening 38of the housing by disposing the edges of the cover in the slot recess 64of the casing section 24 and in a corresponding slot recess in thecasing section 26.

In the circuit breaker 10, the operating handle 14 is formed of a rigiddielectric material such as glass-filled nylon or the like and isprovided with a manually movable portion 14.1 which extends in onedirection from a central bridging portion 14.2 of the operating handle.A pair of legs 14.3 extend in an opposite direction from the centralbridging portion in spaced side-by-side relation to each other to definea clearance space 14.4 therebetween. (See FIG. 9.) Pivot pin means 14.6formed integral with the operating handle on the outer surfaces of eachof the legs 14.3 are fitted into the recess 54 in the casing section 24,and into a corresponding recess in the casing section 26, respectivelyso that the operating handle is mounted for pivotal movement on thehousing 12 with the handle portion 14.1 extending from the housingthrough the housing opening 34 and with the legs 14.3 extending into thehousing chamber 28. In this arrangment, the operating handle is movablefrom the closed circuit position shown in FIG. 8 wherein the operatinghandle portion 14.1 engages a stop surface 34.1 on the housing 12 and anopen circuit position shown in FIG. 10 wherein the handle portion 14.1engages a stop surface 34.2 on the housing 12. Preferably at least oneof the handle legs 14.3 has a stop surface 14.7 thereon and a coilspring 86 is fitted over one of the pivot pin means 14.6 with one springend 86.1 engaged with the stop surface 14.7 and with the opposite springend 86.2 fitted into the recess 54.1 on the casing section 24, therebyto normally bias the operating handle toward the open circuit positionshown in FIG. 10. The legs 14.3 of the operating handle have respectivealigned pivot pin holes 14.8 therein as shown in FIG. 8. The handleportions 14.1 also have holes 14.9 therein for use in multipole circuitbreaker applications as described below.

In accordance with this invention, the circuit breaker 10 also includesa novel and improved collapsible linkage 18 for connecting the operatinghandle 14 to the movable contact arm 76. In this improved linkage orcontrol mechanism, a first link 88, preferably formed of brass or othersuitable strong and rigid material has a central portion 88.1 supportinga pair of spaced integral juxtaposed wings 88.2 giving the first link agenerally U-shaped configuration. The wings 88.2 have respective alignedpivot pin holes 88.3 therein at one end of the link and have respectivealigned rivet holes 88.4 therein at the opposite end of the like. A stop88.5 is provided on the central portion of the link at said oppositelink end. A pivot pin 90 extends through the pivot pin holes 88.3 in thefirst link and through the pivot pin holes 14.8 in the operating handlelegs, thereby to pivotally mount said one end of the first link on theoperating handle, the respective ends of the pin 90 being engaged withthe principal walls of the casing sections 24 and 26 for retaining thepin for free rotation in the holes 88.3 and 14.8. A first latch 92, alsopreferably formed of a strong and rigid material such as steel isdisposed between the wings 88.2 of the first link at said opposite endof the first link, the first latch having a substantial width tosubstantially fill the space between the wings 88.2 while permittingfree movement of the first latch between the wings. A rivet 94 extendsthrough the holes 88.4 in the wings of the first link and through acorresponding hole 92.1 in the latch 92, thereby to pivotally mount thefirst latch on the first link. The latch 92 also extends between thewings 76.3 of the contact arm 76 and a pivot pin 95 extends throughpivot pin holes 76.6 in the contact arm and through a corresponding hole92.2 in the first latch, thereby to pivotally connect the first latch tothe contact arm. Preferably, as is shown in FIG. 12, the pin 95 has acentral protuberance 95.1 positioned within the hole 92.2 in the firstlatch and the opposite ends of the pin fit next to the principal wallsof the casing sections 24 and 26 for retaining the pin for free rotationin the holes 76.6 and 92.2. The first latch has a cam surface 92.3thereon extending laterally out from a line connecting the latch pivotholes 92.1 and 92.2 as shown in FIG. 9. The latch 92 has a substantialwidth tending to minimize wear to the latch surface 92.3. The rivet 94permits the latch plate 92 to pivot on the link 88 between the wings76.3 of the contact arm and is the only rivet used in the linkage 18.

The collapsible linkage 18 then further includes a second link 96, alsopreferably formed of brass or other suitably strong and rigid material.The second link has a central portion 96.1 supporting a pair of spaced,integral, juxtaposed wings 96.2 fitted over the wings 88.2 of the firstlink, thereby also giving the second link a similar, generally U-shapedconfiguration. The wings 96.2 have respective aligned pivot pin holestherein at one end of the second link, these pivot pin holes beingfitted over the pivot pin 90 for pivotally mounting the second link 96on the first link 88. The wings 96.2 of the second link also haverespective aligned pivot pin holes 96.4 therein at the opposite end ofthe second link. A cam follower roller 98 also preferably formed of arigid brass material or the like is disposed between the wings 96.2 ofthe second link and a pivot pin 100 extends through the pivot pin holes96.4 in the second link and through a corresponding central hole 98.1 incam follower roller for rotatably mounting the roller on the secondlink, the opposite ends of the pin 100 being engaged with the principalwalls of the casing sections 24 and 26 for retaining the pin for freerotation in the holes 96.4 and 98.1. In this arrangement the second linkis proportioned for pivotal movement from a first position to a secondposition. In the first position of the second link, the cam followerroller 98 is engaged with the cam surface 92.3 on the first latch formanually holding the first latch 92 in a latching position thereof. Astop 88.5 on the first link is positioned adjacent the latch 92 in thelatching position thereof as a limit to possible latch movement for apurpose to be noted below. In the second position of the second link,the cam follower roller 98 disengages the first latch cam surfacepermitting the first latch to rotate to an unlatching position thereofin response to the bias of the springs 84 which normally bias thecontact arm 76 to the open circuit position of the circuit breaker. Theroller 98 has substantial width engaging the cam surface 92.3 forminimizing roller wear. Further, because the roller 98 engages a camsurface 92.3 rather than a latching nose or the like, the latch androller are not subject to excessive wear. The diameter of the roller 98is significant in determining the force with which the roller bearsagainst the cam surface 92.3 and accordingly, the roller diameter can bevariably specified for varying the forces necessary to operate thebreaker 10.

In the collapsible linkage 18 of this invention, the second link 96 isalso provided with respective aligned slots 102 in the wings 96.2 of thesecond link, each of these slots having first and second portions 102.1and 102.2 which are oriented at an angle relative to each other. Asecond latch member 104 constituting a latch pin is pivotally mountedwithin the slots 102 for movement between the two portions of the slots.That is, a pivot pin 106 is mounted for free rotation in pivot pin holes88.6 in the first link so that the pin 106 is retained in those holes bypositioning of the ends of the pin adjacent the principal walls of thecasing sections 24 and 26. Keeper links 107 each have one end fittedover the respective ends of the pin 106 to extend between the wings 96.2of the second link and have their opposite ends fitted over the secondlatch pin 104, the ends of the second latch pin being engaged with thewalls of the casing section 24 and 26. Preferably, bushings 107.1 formedon the keeper links at said one end are also engaged with the walls ofthe casing sections 24 and 26 for assuring proper positioning of thekeeper links. As the keeper links are subjected to only relatively lightstresses, the keeper links are desirably molded of a snythetic plasticmaterial such as glass-filled nylon or the like for achieving accurateconstruction at low cost. In this arrangement, the keeper links normallysupport the second latch pin in a latching position in the firstposition 102.1 of the slots in the second link, whereby the latch pinnormally holds the second link in its first position with the camfollower roller 98 engaged with and holding the first latch 92 in thelatching position of the first latch. However, the second latch pin 104is adapted for pivotal movement as supported by the keeper links to moveinto the second portions 102.2 of the second link slots for permittingthe second link to move to its second position and for permittingunlatching of the first latch 92.

Finally, the collapsible linkage 18 includes a tripping member 108 of abell-crank shape which is mounted for pivotal movement on the first link88 from a first position normally holding the second latch pin 104 inits latching position to a second position releasing the second latchpin for movement to its unlatching position when the tripping member ispivoted in response to application of an actuating force as is furtherdiscussed below. That is, the first link 88 has tripping member pivotpin holes 88.7 located in the first link wings 88.2 and a pivot pin 110is extended through the holes 88.7 and through a corresponding pivot pinhole 108.1 in the tripping member so that the ends of the pin 110 aredisposed adjacent respective wings 96.2 of the second link for retainingthe pin 110 in such pivot pin holes between the wings 96.2. The trippingmember 108 has a first arm 108.2 extending from a central bushingportion 108.3, the arm 108.2 having a latch surface 108.4 formed in oneside of the arm for normally engaging and holding the second latch pin104 in its latching position when the tripping member is in its firstposition. The tripping member 108 also has a second arm 108.5 angularlydisposed relative to the first arm 108.2, the second arm having aclearance slot 108.6 fitted over the pivot pin 90 which mounts the firstlink and having an actuating nose 108.7 at the end of the second arm tobe struck by the clapper for moving the tripping member to its secondposition. Preferably the tripper arm 108.2 has a pair of rod-likeportions 108.8 extending laterally from respective opposite sides of theend of the arm 108.2 for use when the breaker is adapted for multipoleapplication as described below.

A coil spring 112 fitted over the pivot pin 106 has one end 112.1engaged with the first link 88 (or alternately with the second latch pin104) while its opposite end 112.2 is engaged with the tripping member108 for normally biasing the tripping member to its first position. Thespring 112 is proportioned to provide only a relatively light biasingforce to the tripping member.

In accordance with this invention, the dual-latch collapsible linkagesystem 18 of this invention incorporates components which are soproportioned relative to each other so that cumulative mechanicaladvantages are achieved, whereby the linkage 18 is adapted to move themovable contact arm 76 between open and colosed circuit positions withsubstantial force but whereby the linkage is adapted to be collapsed bythe application of a relatively much smaller and consistently uniformforce to the actuating nose 108.7 of the tripping member of the linkage.That is, the first latch and the first and second links are proportionedso that the force applied to the first latch by the contact arm tendingto rotate the first latch in a clockwise direction (as viewed in FIG. 8)around the pin 94 has a relatively small moment arm as compared to theforce applied to the first latch by the cam follower roller 98 whichtends to rotate the first latch in a counterclockwise direction. Second,the cam follower roller, second link, second latch pin and keeper linksare proportioned so that, although the first latch applies a significantforce to the second link tending to rotate the second link to its secondposition around the pivot pin 90, that force has a very small moment armrelative to the pin 90 whereas the force exerted by the second latch pin104 tending to restrain such rotation of the second link around the pin90 has a greater moment arm. Further, because of the incline of theslots 102 in the second link, only a part of the force applied to thesecond latch pin by the second link tending to move the second latch pinis effective to move the second latch pin toward its unlatchingposition. Third, the second latch pin 104, the tripper 108 and the slots102 in the second link are proportioned and located so that the forceexerted on the tripper 108 by the second latch pin 104 is directedsubstantially in line with the pivot pin 110. As a result, that forcehas almost no moment arm tending to rotate the tripper in eitherdirection around the pivot pin 110. However, the light frictional forcebetween the latch surface 108.4 of the tripping member and the secondlatch pin 104 has a substantial moment arm relative to the pin 110tending to restrain such clockwise rotation of the tripper member.Finally, the light frictional force between the latch surface 108.4 oftripping member and the second latch pin 104 has a moment arm relativelysmaller than the moment arm of a force applied to the actuating nose108.7 of the tripping member. According, the linkage 18 is adapted tohold the contact arm 76 in closed circuit position with a substantialforce while only a relatively light, consistently uniform force need beapplied to the actuating nose of the tripping member for initiatingcollapsing of the linkage 18.

In accordance with this invention, the tripper member 108 is desirablyformed of precision molded thermoplastic or thermosetting high lubricitymaterial for assuring that the tripping member is precisely proportionedat low cost, whereby the linkage 18 is adapted to be readily assembledwith assurance that the linkage properly performs its functions ashereinafter described without requiring any cutting, bending or trimmingof the linkage components as they are assembled together. For example,the tripping member 108 is desirably formed of a glass-reinforcedthermoplastic polyester resin such as is sold by General ElectricCompany under the designation "Valox". Because the tripping member 108is subjected to such low forces in the linkage 18 as above described,the latch surface 108.4, for example, of the member is not subject tocold flow or other detrimental variation in configuration even over along service life. However, the tripper is readily formed of thismaterial by molding so that the tripping member is preciselyproportioned for easy assembly of the linkage. Further, because thetripping member is formed of a synthetic plastic material the tripperhas high lubricity relative to the second latch pin 104 so that noinitial lubrication of the linkage 18 is required during use of thecircuit breaker 10. In addition, such tripper materials do not tend tobe subject to corrosion even in hostile environments and do not tend tostick to metal members with which they are in pressure engagement. Thetripper is also light in weight, and the engagement of the latch pin 104with the tripper is in a direction transverse to the direction in whichthe weight of the tripper might tend to move the tripper. Accordingly,the linkage 18 is highly resistant to shock even though the linkagecomponents have substantial mass and strength.

In the circuit breaker 10, the previously noted magnetic actuating coil75 is preferably wound on a plastic spool 114 best seen in FIG. 9 whichincludes a hollow, tubular, central portion 114.1, a base 114.2 having aflange 114.3 which fits around the coil support arm 68.4 of the framefor properly positioning the spool on the frame, and a stop 114.4 at theopposite end of the spool engaging the frame 68 for properly mountingthe coil 75 within the chamber 28. The spool 114 also preferably has aplurality of integral flexible fingers 114.5 extending upward from thespool and has a locating abutment 114.6 standing up from the top of thespool. A magnetic core means 116 for the actuating coil 75 has a centralrod-like core portion 116.1 to fit within the coil 75, has a large capor pole face 116.2 at one end of the central portion, and has a mountingflange element 116.3 at one end thereof. Preferably the mounting flange116.3 is of generally rectangular shape as viewed along the axis of thecore means and has key-slot aperture 116.4 receiving the cap 116.2therein. In FIGS. 8-11, the core means 116 is illustrated as a solidcore (such as would be normally used in instantaneous trip operation)for the actuating coil 75 so that the central portion 116.1 comprises arod of annealed iron or the like. However, as is discussed furtherbelow, the core means could also be of the time delay type.

In accordance with this invention, the core means is mounted in thechamber 28 by disposing edges of the core mounting flange 116.3 in therecess 60 in the casing 24 and in a corresponding recess in the casing26, by fitting the flange locating hole 116.5 over the locating abutment114.6 on a coil spool to secure the cap 116.2 in the key slot, byextending the central core portion 116.1 through the spool 114, bydisposing the end of the central core portion opposite the mountingflange into the recess 60.1 in the casing 24 and in a correspondingrecess in the casing 26, and by engaging the core mounting flange 116.3with the resilient fingers 114.5 on the spool for biasing the core to aconsistent position in its mounting recess 60. In this arrangement, thecoil 75 is easily and accurately mounted in the circuit breaker 10 andthe core means 116 is also mounted with ease and accuracy relative tothe coil, thereby to assure that the pole face 116.2 of the core meansextends across a substantial part of the width of the housing chamber 28and is accurately positioned in the chamber 28 relative to the pole face68.2 of the magnetic frame in the chamber. The core and coil means arethus easily assembled without requiring that any soldering, welding orcold heading operations be performed at assembly. Accordingly, there isno risk that the core or the frame 68 will be subject to materialstresses such as work-hardening such as might permit residual magnetismto build up in the core or frame during use of the circuit breaker 10.Further if disassembly of the breaker 10 is required for any reason, thecoil, core and frame components of the breaker are easily recoverablewithout damage thereto for reuse if desired.

In the circuit breaker 10, a magnetic clapper 118 is also mounted on thecasing sections 24 and 26 to be precisely located in the chamber 28relative to the pole face 116.2 of the core, to the pole face 68.2 ofthe frame and to the actuating nose 108.7 of the tripper in the linkage18. That is, the clapper 118 formed of a magnetically permeable metalmaterial such as steel or iron has a generally flat, striplikeconfiguration, has an actuating end 118.1 slightly inclined relative tothe remainder of the clapper, has a pair of integral pintles 118.2spaced a selected distance from the end 118.1 and a shorter distancefrom the opposite end of the clapper, has an integral biasing tab 118.3struck up from the clapper intermediate the pintles and the inclined end118.1, has an integral locating tang 118.4 struck down from the clapperadjacent the pintles between the pintles and the opposite end of theclapper, and having an additional deformation 118.5 at said opposite endof the clapper. A compact counterweight member 120 formed with a slot120.1 therein is then press fitted over the deformed portion 118.5 ofthe clapper. The counterweight is preferably of a magnetically permeablematerial and of a configuration to depend downwardly alongside a portionof the coil 75 for a purpose to be discussed below.

In accordance with this invention, the clapper 118 is mounted in thecircuit breaker 10 by disposing the pintles of the clapper so that onepintle fits against the locating abutments 62 and 62.1 in the casingsection 24 and so that the other pintle fits against correspondingabutments in the casing section 26, the locating tank 118.4 of theclapper then being engaged behind the locating abutment 62.2 of thecasing 24 and behind a corresponding abutment in the casing 26. In thisarrangement, when a biasing spring 122 to be discussed further below isengaged with the clapper biasing tang 118.3, the clapper 118 isprecisely mounted for pivotal movement in the chamber 28 between a restposition in which the clapper engages a stop 63 in the casing section 24(see FIG. 7) and an actuating position wherein the clapper is engagedwith the pole face 116.2 of the magnetic core means 116, with the poleface 68.2 of the magnetic frame, and with the actuating nose 108.7 ofthe tripper in the linkage 118. The clapper strip also extends acrossthe full width of the chamber 28. The clapper weight is such thatpivotal movement is substantially counterbalanced by the counterweight120 and the clapper is normally biased to its rest position by thespring 122. The clapper shape is very simple so there is little tendencyfor damage or distortion to occur during annealing of the clapper andother clapper handling prior to assembly. However the clapper is adaptedfor precise pivotal movement on the knife edges formed by the edges ofthe clapper pintles adjacent to the locating tang 118.4 and is preciselylocated in the chamber 28.

In this arrangement of the actuator coil 75, the frame 68, the coremeans 116 and the clapper 118, a magnetic circuit is established fromthe frame 68 through the core means 116 to a portion of the clapper 118,and back to the frame through the frame pole face 68.2. In this magneticcircuit, the principal magnetic reluctance results from the air spacingof the clapper 118 from the pole face 116.2 of the core and from thepole face 68.2 of the frame. When electrical current flows in the coil75 as hereinafter described, the magnetic field established by suchcurrent is directed through the noted magnetic circuit. In normalcircuit breaker operation, such a magnetic field is insufficient toeffect any movement of the clapper 118 against the bias of the spring122. However, if a larger overload current is directed through the coil75, the magnetic clapper 118 is magnetically drawn against the polefaces 68.2 and 116.2 for moving the clapper from its rest position toits actuating position. Of course, the proportions of the coil 75 arevaried as desired to adapt the circuit breaker 10 for D.C. or 50, 60, or400 hertz A.C., operation for operation in response to overload voltagesin the breaker circuit. The cores 116 and springs 122 are also adaptedto be readily changed for adjusting the circuit breaker operating rangesand the like.

The circuit breaker of this invention also includes a novel and improvedcalibration system 22 which is shown to include a calibrating member 124preferably formed of a precision molded plastic material. Thecalibrating member has a first portion 124.1 adjacent one end which ismounted for free rotation in the opening 36 in the housing, a flange124.2 to engage the casing section 24 and 26 for preventing axialsliding of the calibrating member in the opening 36 and an outer endflange 124.3 for substantially closing the housing opening 36, thisouter flange having a slot or key recess in its outer surface for use inrotating the calibrating member as will be understood. The calibratingmember also has an integral screw-threaded portion 124.4 which is freelyrotatable in the recess 66 in the casing section 24 with the remainderof the calibrating member and has a reduced diameter portion 124.5 ofits opposite end fitted into the casing recess 66.1 for permittingrotation of the member while retaining its axial alignment in the casingrecess 66. The casing section 26 is fitted over the recesses 66 and 66.1for retaining the calibrating member therein. The spring 122 preferablycomprises a coil tension spring having a convolution 122.1 at one endfitted over the biasing 118.3 of the clapper and having a convolution atits opposite end fitted over the screw-threaded portion of thecalibrating member and threadedly engaged with that portion of themember in the manner of a one-thread nut, thereby to apply a biasingforce to the clapper tending to hold the clapper in its rest position.The calibrating member 124 is located on the housing 12 so that rotationof the calibrating member is adapted to threadedly advance the springend 122.2 along the threaded portion 124.4, thereby to vary thedirection in which the force of the spring 122 is applied to the clapperwithout substantially altering the tension to which the spring issubjected. In this way the noted movement of the spring 122 changes themoment arm (relative to the pintles of the clapper) with which thespring biasing force is applied to the clapper for changing the level offorce holding the clapper in its rest position thereby to calibrate thecircuit breaker 10. To allow use of a low rate spring for limitingbuildup of clapper bias during clapper rotation to achieve snappierclapper action, the spring preferably has an initial tension so thatadequate bias force is obtained with minimum spring extension, therebysaving spring space.

The circuit breaker is easily calibrated by rotation of the member 124which is conveniently accessible from outside the breaker on the topsurface of the breaker adjacent the operating handle 14. The calibrationsystem is very compact and is therefore easily located in this desirablyaccessible position in the breaker. As the member 124 does not moveaxially during calibration, the member remains accessible as it isrotated and is therefore amenable to automated calibration. The spring122 does not tend to cause rotation of the calibration member 124 sothat when adjustment is made, there is no backlash in the adjustment andno locking means is required for holding the calibrating member in itsposition of adjustment during use of the circuit breaker. Where desired,a drop of glyptal is applied over the housing opening 36 aftercalibration to deter tampering with the calibration setting. Further,the calibrating member has a substantial number of fine screw threads sothat many revolutions of the calibrating member are required to adjustthe calibration throughout its desired range. Thus, high resolutioncalibration of the breaker is achieved. Also, when the spring end 122.2has been advanced to one end or the other of the screw threaded portionof the calibrating member, the spring end 122.2 merely slips if thecalibrating member is further rotated. Thus, there is no risk thatcalibration can result in damage to the calibration system if excessiverotation of the calibrating member is attempted Further, because thestress on the spring 122 is not substantially changed during adjustmentor calibration of the breaker, the spring rate of the spring need not beprecisely controlled while still permitting achievement of excellentbreaker calibration. Further, because the spring is a tension spring,there is no tendency for spring convolutions to bind against each otherto cause errors in the calibration. The spring 122 is preferablyprovided with a relatively low spring rate so that when the clapper 118is moved to its actuating position as described below, the spring 122does not apply any significantly greater torque to the clapper such asmight reduce the effectie clapper force at the moment the clapperstrikes the actuating nose of the tripper 108.

The circuit breaker 10 is adapted to achieve consistently, uniformoperation as is hereinafter described. That is, with the circuit breaker10 in a closed circuit position as illustrated in FIG. 8, a circuitextends from the load terminal 51, through the coil 75 to the fixedcontact 72 carried by the terminal 52, through the contacts 78 and 80,the bifurcated ends 76.1 and 76.2, and the intermediate portion 76.4 ofthe movable contact arm to the fixed contact 74 carried by the terminal50. If desired for connecting the breaker 10 for conventional shunt tripoperation, exterior electrical connection can be made to the terminal52. The movable contact arm 76 is normally held in its closed circuitposition bridging the contacts 72 and 74 as shown in FIG. 8 bydisposition of the operating handle 14 in its closed circuit position tohold the collapsible linkage in an overcenter position. That is, whenthe position shown in FIG. 8, the pivot pin 90 is disposed to the rightof a line between the pivot pin 94 and the pivot pin means 14.6 on theoperating handle under bias from the contact arm spring 84. The firstlatch 92 is normally held in its latching position by engagement of thecam follower roller 98 with the cam surface 92.3 of the first latch. Thesecond link 96 is normally restrained in its first position holding theroller 98 engaged with the cam surface 92.3 by the engagement of thesecond latch pin 104 in the slots 102 of the second link. The secondlatch pin is held in its latching position by the tripper 108. The arm108.5 of the tripper is disposed in the clearance slot 68.3 of the framewith the actuating nose 108.7 positioned a precise distance above thepole face 68.2 of the frame. The clapper 118 is disposed in its restposition under a predetermined bias as determined by the adjustment ofthe calibration system 22. In this situation, normal current flows inthe noted breaker circuit.

If manual opening of the breaker circuit is desired, the operatinghandle 14 is manually moved to its open circuit position moving thepivot pin 90 through an overcenter position to the left of the linebetween the pivot pin 94 and the pivot pin means 14.6 on the operatinghandle. As the pivot pin moves across that noted line, restraint of themovable contact arm 76 is released and the arm moves to its open circuitposition under the bias of the spring 84, thereby moving the linkage 18to the position shown in FIG. 10. As initial circuit opening movement ofthe contact arm 76 occurs, when arcing between the mating contact pairs72-78 may occur, the magnetic field established around the terminals 50and 52 and around the bifurcated ends of the contact arm by the currentstill flowing in the breaker circuit, keeps the noted arcs separatedfrom each other and deflects the arcs away from the contact arm to bevented from the breaker and extinguished as the arcs pass through thegridded aperture in the arc chute member. During such manual opening ofthe breaker circuit, the first latch 92, the second latch pin 104 andthe tripping member 108 generally remain in their positions relative toeach other as illustrated in FIG. 8.

However, if an overload current occurs in the breaker circuit, themagnetic field established by the flow of such overload current isdirected through the main magnetic circuit of the breaker as previouslydescribed. The clapper 118 then moves sharply from its rest position(see FIG. 8) to its actuating position, thereby striking the actuatingnose 108.7 of the tripper of the linkage 18 to initiate collapsing ofthe linkage. That is, the tripper 108 is rotated to its second positionon the pin 110 for releasing the second latch pin 104. The second latchpin moves in the slots 102 in the second link permitting the second linkto ride off the cam surface of the first latch 92 for permitting thefirst latch to rotate under bias of the spring 84 and for permitting themovable contact arm 76 to move sharply to its open circuit position asthe collapsing of the linkage 18 occurs. A position of the circuitbreaker components at this collapsing of the linkage occurs isillustrated in FIG. 11. Subsequently, the operating handle 14 then movesto its open circuit position under the bias of its spring 86, thismovement of the operating handle further moving the linkage to theposition shown in FIG. 10 wherein the tripper, the second latch pin, andthe first latch are returned to their latching positions for resettingthe circuit breaker to permit manual reclosing of the circuit breaker.The stop 88.5 on the first link 88 assures that the first latch 92 isproperly positioned for such resetting by limiting counterclockwiserotation of the first latch. The movement of the linkage to its restposition snaps the tripper against the clapper 118 to assure that theclapper is returned to its rest position and does not tend to stick tothe magnet pole faces 68.2 and 116.2 due to any residual magnetism. Ifmanual reclosing of the circuit breaker is attempted while theovercurrent condition still exists in the circuit monitored by thebreaker, reclosing of the breaker contacts results in immediate movementof the clapper 118 to cause collapse of the linkage 18 and reopening ofthe breaker circuit. Thus the breaker displays trip-free operation andcannot be held in closed circuit position while such an overcurrentcondition continues.

It should be noted that, when the operating handle 14 is manually movedto its open circuit position while the clapper 118 is in its restposition, the clapper fits into the clearance space 14.4 in theoperating handle. In this clapper position, the tripper nose 108.7 ispositioned to interface with the extending end of the clapper portion118.1 for blocking any possible movement of the clapper against the polefaces of the frame and core means. Accordingly, the clapper is notthereafter movable to its actuating position even when an overloadcurrent should be direct through the coil 75 between the terminals 51and 52. This feature of the circuit breaker 10, referred to as "clapperblocking", facilitates testing and some forms of calibration of thecircuit breaker wherein it is desired to direct selected current levelsthrough the coils in an automated testing operation without requiringresetting of the circuit breaker after each such test. For example, suchclapper blocking permits the core rod in a time delay core means to bepositioned at the internal core pole face by applying an overloadcurrent to the coil, thereby to permit subsequent device calibratingadjustment without requiring any manual blocking of the clapper.However, test openings 42 are also provided in the breaker housing forpermitting manual movement or blocking of the clapper 118 where thatshould be desired.

It should also be noted that the circuit breaker 10 provides a novel andimproved arrangement of the clapper 18 relative to the frame pole face68.2 and to the actuating nose 108.7 of the linkage tripper. In thisregard it will be understood that, as the clapper 118 is magneticallymoved from its rest position to its actuating position the magneticfield causing this movement is progressively increased in strength asthe clapper approaches the pole face 68.2 and as the magnetic reluctancecaused by the spacing of the clapper from that pole face isprogressively decreased. Accordingly, the clapper is desirably adaptedto strike the actuating nose 108.7 very close to the plane of the poleface 68.2 when the clapper force is large to assure that trippermovement is initiated. On the other hand, it is desirable that, afterthe clapper initially strikes the actuating nose, the clapper besubjected to additional movement of significant length to assure thatthe rotation of the tripper resulting from additional clapper movementis sufficient to assure proper tripping of the linkage 18. In previouslyknown circuit breakers, the spacing of the clapper relative to theactuating nose of the tripper had been a source of considerabledifficulty during assembly in attempting to achieve the propercompromise between these two conflicting considerations. This problemhas also resulted in many malfunctions during use where the clappermight strike the tripper with inadequate force to move the tripper orwhere the clapper travel after impact with the tripper was ineffectiveto initiate opening of the breaker circuit. In the circuit breaker 10,the actuating nose 108.7 is provided with an actuating cam surface 108.9which in inclined relative to the surface of the clapper adapted toengage that surface, whereby the point of initial engagement of theclapper with the nose occurs at cam surface portion A on the surface108.9 as illustrated in FIG. 14 thereby to assure that the clapper isclose enough to the pole face 68.2 to have the desired impact force onthe tripper. However, as the tripper rotation occurs, the point ofengagement between the clapper and the tripper surface moves alongsurface 108.9 to the cam riser surface portion B as illustrated in FIG.15, thereby to provide a relatively greater stroke or travel of thetripper to assure that the tripper rotation is adequate to initiateopening of the breaker circuit.

The circuit breaker 10 as above described is also characterized by amodular construction which facilitates low cost adaptation of thebreaker for other types of current breaker applications such as areshown in FIGS. 16-26 which illustrate other, alternate preferredembodiments of the circuit breaker of this invention. Where componentsof these other alternate embodiments of the invention incorporatecomponents corresponding to those illustrated and described above withreference to the circuit breaker 10, those components are indicated bycorresponding numerals.

For example, in an alternate preferred embodiment of the circuit breakerof this invention as indicated at 126 in FIG. 16 the circuit breaker isadapted for series trip operation by substituting a shorter stubterminal 128 for the terminal 52, the terminal 28 having the fixedcontact 78 mounted thereon but being relatively shorter than theterminal 52 so it does not extend as far through the bottom opening 38in the housing 12. The stub terminal is still accessible for use iftesting of the coil 75 should be required or if a group of breakers areto be connected with the coils alone arranged in series for calibration.

In another alternate embodiment of this invention indicated at 130 inFIG. 17, a terminal 132 is mounted in the housing openin 38 in additionto the terminal 52 used in the circuit breaker 10, the terminal 132(instead of the terminal 52) being electrically connected to the coilend 75.2 within the circuit breaker for adapting the breaker forconventional relay-trip type of circuit breaker operation.

In another alternate embodiment of this invention indicated at 134 inFIGS. 18-20, the circuit breaker is adapted for auxiliary switch type ofcircuit breaker operation. In this embodiment of the invention, thebreaker incorporates a novel and improved auxiliary switch structureindicated generally at 136 which is adapted for easy assembly within thecircuit breaker and which is adapted to be operated as a single poledouble throw switch without subjecting the other circuit breakercomponents to such forces as would interfere with proper operation ofthe circuit breaker. In this embodiment of the invention, a terminal 138is substituted in the housing 12 for the terminal 52, the contact 72 andthe actuator coil end 75.1 being connected to the terminal 138. Theconfiguration of terminal 138 thus frees the housing opening 38 toaccommodate the switch 136; the cover 77 is omitted from the opening 38;and casing recesses 138.1 and 138.2 (see FIG. 7) receive correspondingtangs on the terminal 138 to assist in locating the terminal 138 in thehousing 12.

The auxiliary switch 136 comprises a bottom casing section 140 of adielectric material which has terminal openings 140.1, 140.2 and 140.3therein, has a flange 140.4 fitted into recesses 64 in the casingsection 24 and in a corresponding recess in casing 26 for mounting theswitch on the housing 12, has guide grooves 140.6 therein, has anovertravel guide groove portion 140.5, and has a pin 142 mounted on thecasing section 140. Terminals 150, 152 and 154 are mounted in therespective openings in the bottom casing section and have mounting tabscrimped to the bottom casing section. A resilient, conductive contactarm 156 is secured to the terminal 154 to extend in cantilever relationtherefrom and carries contct means 156.1 at its distal end for movementbetween respective positions engaging contacts on terminal ends 150.1and 152.1 for closing alternate circuits between terminals 152-154 andterminals 150-154. An actuator 146 has a main portion 146.1 slidable inthe casing guide groove 140.6, has an opening 146.2, has an abutment146.3 engaged with the contact arm 156, and has a pair of spacedportions 146.4 extending from the casing section 140 to engage themovable circuit breaker arm 76. A pair of springs 158 are fitted overthe pin 142, each having one spring end 158.1 abutting the casing 140and the opposite spring end 158.2 fitted into the actuator opening 146.2normally biasing the actuator to the position shown in FIG. 18. A cover144 is preferably positioned over the top of the casing 140 and isfitted between the actuator portion 146.4 to be held in place byengagement with abutment 144.1 on the circuit breaker casing sections 24and 26.

In operation of the auxiliary switch 136, the actuator 146 is normallyheld in the position shown in FIG. 19 by engagement with the circuitbreaker contact arm 76 when the circuit breaker is in closed circuitposition, the actuator being held in this position against the bias ofthe springs 158 so that the switch contact arm engages the contact means156.1 with the terminal end 152.1 to close a first switch circuitbetween terminals 152 and 154. In this circuit position the pressureengagement between the contact means 156.1 and the terminal end 152.1 isdetermined by the resilience of the contact arm 156. When the circuitbreaker contact arm 76 is moved manually or automatically to opencircuit position, the actuator 146 is moved to the position shown inFIG. 18 in response to bias of the springs 158, the movement of theactuator moving the switch arm 156 the engage the contact means 156.1with the terminal end 150.1, thereby to open the first switch circuitand to close a second switch circuit between terminals 150 and 154.

In this arrangement, the switch contact arm 156 is provided with onlythe degree of resilience necessary to achieve the desired contactpressure between the contact means 156.1 and the terminal end 152.1.Accordingly, substantially all of the force applied to the circuitbreaker contact arm 76 by the switch 136 results from the bias of thesprings 158 even as the switch 136 is moved through its two contactpositions. For example, even where the circuit breaker contact arm 76 issubjected to overtravel during closing of the breaker circuit as aresult of the resilient mounting of that arm and as a result of movementof the breaker linkage 18 through an overcenter position, the actuator146 easily slides into the overtravel portion 140.5 of the guide groovesin the bottom casing section and the principal switch force resistingsuch overtravel of the contact arm 76 results from the bias of thesprings 158 which preferably have a low spring rate and a preciselypredetermined torque output. The fact that the switch arm 156 changesfrom a simple cantilever beam to a propped cantilever beam during suchovertravel after the arm engages the terminal end 152.1 does not resultin several fold increase in the forces applied to the circuit breakerarm 76 as occurred in previously known auxiliary switch arrangements.That is, since the arm 156 no longer bears against the actuator 146after the arm 156 engages the terminal 152.1, the circuit breaker 135operates in a consistent manner regardless of the circuit position ofthe auxiliary switch and is not subject to such high and varying forcesby the switch as might create undesirable variations in circuit breakeroperation due to excessivve loading of the latches in the linkage 18.The switch 136 is also adapted to be assembled and tested beforemounting in the breaker 135. If desired, the springs 84 may be changedto provide a different bias to the arm 76 where the auxiliary switch 136is used.

In another preferred embodiment 160 of the circuit breaker of thisinvention as illustrated in FIG. 21, the circuit breaker is adapted forflux switch type of circuit breaker operation so that the circuitbreaker is adapted for use where high but brief transient currentoverloads are likely to occur and where it is desired that the circuitbreaker tolerate such brief transients without nuisance tripping. In thecircuit breaker 160, the instantaneously operating type of magnetic coremeans 116 used in the circuit breaker 10 is preferably replaced with atime-delay type of magnetic core means 162 as shown in FIG. 21. In thetime-delay core means a core member 162.1 of annealed steel is slidablymounted in an open ended tube 162.2 of non-magnetic brass or the likeand is biased to one end of the tube by a coil spring 162.3, the tubebeing otherwise filled with a liquid 162.4 and having its open endsealed with a cap 162.5 of magnetically permeable material swaged to thetube. When such a time-delay core means is disposed inside a magneticactuator coil with the cap end of the core means disposed adjacent amagnetic clapper to correspond to the pole face 116 of the core meansshown in the circuit breaker 10, the occurrence of an overload currentin the coil establishes a magnetic field which tends to draw the core162.1 to the cap end of the core means against the bias of the spring162.3, the movement of the core to the cap end being delayed in themanner of a dash-pot by the liquid 162.4 in the core means. When such atime-delay core means is used, the magnetic circuit partially formed bythe core means has a large initial reluctance resulting from the largeinitial spacing of the core 162.1 from the internal end of the cap162.5. The clapper is therefore moved to its circuit breaker actuatingposition only with a time delay after the occurrence of the notedcircuit overload when the core 162.1 has moved to the cap end of thecore means. As the above-noted structural features and method ofoperation of a time-delay core means are conventional and are shown inU.S. Pat. No. 3,900,810 for example, those features are not furtherdescribed and it will be understood that the time-delay core means 162is adapted to function in a conventional mannner. In accordance withthis invention, however, the core means 162 further includes a flangeplate 162.6 secured to the cap 162.5, the flange plate having agenerally rectangular configuration as viewed axially along the coremeans and having an aperture 162.7 therein. Preferably the plate 162.6has another aperture therein and the cap 162.5 is fitted through theplate aperture and is swaged to the tube 162.6 for securing the flangeplate to the cap 162.5. In the circuit breaker 160, the core means 162is then mounted in the circuit breaker by disposing the edges of theflange plate 162.6 in the recess 60 of the casing section 24 and in acorresponding recess in the casing 26 and by fitting the aperture 162.7over the locating abutment 114.6 on the coil mounting spool, thereby tomount the core means 162 in the manner of the core means 116 shown inthe circuit breaker 10.

In the circuit breaker 160, an auxiliary flame or flux guiding magneticcircuit segment member 164 is also utilized, the flux member having anapertured base part 164.1 thereon, having base flange portions 164.2 and164.3 which fit into recesses 164.4 and 164.5 in the casing section 24(see FIG. 7) and in corresponding recesses in the casing 26, and havingan arm 164.6 which extends alongside the coil 75 so that the distal endof the arm is spaced closely adjacent to depending counterweight 120 onthe clapper 118. As previously noted, the counterweight 120 ispreferably of magnetically permeable material. Desirably, anelectrically insulating sleeve (not shown) is fitted over the arm 164.6to avoid any contact between the arm 164.6 and the end 75.1 of theactuating coil or the terminal 51.

In this arrangement of the flux type circuit breaker 160, the circuitbreaker has a main magnetic circuit extending from the frame 68, throughthe core 162.1 and a portion of the clapper 118 to the frame pole 68.2,the principal magnetic circuit resulting from the spacing of the clapper118 from the pole face 68.2 and the cap 162.5 and the spacing of thecore 162.1 from the internal side of the cap 162.5. The circuit breakeralso has an auxiliary magnetic circuit extending from the auxiliaryframe or flux member arm 164.6, through the core 162.1, through portionsof the clapper 118 and through the counterweight 120 back to the memberarm 164.6. The principal reluctances in this auxiliary magnetic circuitresult from the spacing of the counterweight 120 on the clapper 118 fromthe auxiliary frame arm 164.6 and from the cap 162.5 of the core meansand the spacing of the core member 162.1 from the internal side of thecap 162.5. If the core member 162.1 is in the down position shown inFIG. 21 when an overload current occurs in the coil 75, the auxiliarymagnetic circuit initially receives a significant share of the magneticflux produced by the overload current. The flux of the main magneticcircuit initially tends to draw core 162.1 toward the cap end of thecore means and tends to draw the clapper 118 into the engagement withthe pole face 86.2 on the frame. However, the flux initially occurringin the auxiliary magnetic circuit tends to resist any such movement ofthe clapper 118. Thus, movement of the clapper in response to the mainmagnetic circuit is initially resisted both by the calibrating spring122 and by a reverse torque applied by the auxiliary magnetic circuit sothat clapper movement does not occur and the circuit breaker is nottripped by a brief transient overload current. Thus the circuit breaker160 displays improved resistance to nuisance tripping in response to theoccurrence of even very high transient current overloads, such breakersbeing adapted to withstand transients of 25-30 times the breaker ratingwhere the transient duration is on the order of a few milliseconds.

However, if the overload current condition continues so that the core162.1 is moved toward the cap end of the core means, this core movementchanges the spacing between the core 162.1 and the cap 162.5 which iscommon to both magnetic circuits. This change of spacing decreases thereluctance in the main magnetic circuit but does not decrease thereluctance of the auxiliary magnetic circuit to the same extent. Thatis, the core movement in moving the bottom end of the core 162.1 awayfrom the flux member 164 tends to provide an increasing spacing betweenthe core and the flux member which maintains the reluctance of theauxiliary circuit at a relatively constant level. Accordingly, movementof the clapper occurs only when movement of the core changes thereluctance of the main magnetic circuit to the point where the torqueforce applied to the clapper by the main magnetic circuit overcomes theretarding force of the spring 122 and of the auxiliary magnetic circuit.However, once clapper movement is initiated, the reluctance of the mainmagnetic circuit decreases as the clapper movement reduces its spacingrelative to the pole face 68.2 while the reluctance of the auxiliarymagnetic circuit begins to increase as the counterweight 120 moves awayfrom the flux member arm 164.6. In this way the change in forces on theclapper has an avalanche effect providing especially sharp movement ofthe clapper to its actuating position. In this way, the circuit breakerachieves not only increased resistance to nuisance tripping in responseto brief transient current overloads but also achieves sharper clappermovement for improved circuit breaker tripping when the overload currentcontinus for a longer period of time.

In another alternate embodiment 166 of the circuit breaker of thisinvention as illustrated in FIGS. 22-26, breaker 10 is adapted formultipole application. A double-sided casing section 168 is utilizedbetween each pair of adjacent poles of the multipole breaker, one side168.1 of the casing section having edge walls and interior casingfeatures corresponding to those provided on the casing section 24 aspreviously described and the other side 168.2 of the casing sectionhaving edge walls and interior casing features corresponding to thoseprovided in the previously described casing section 26. One or more ofthe casing sections 168 are then fitted together with each other, andwith one each of the casing sections 24 and 26 as shown in FIGS. 22, 23and 25, to form a housing defining a plurality of chambers 28 within thebreaker 166. The single housing section 168 is readily combined with thesingle pole section 24 and 26 to build up any desired multipole devicein a compact and efficient manner. The exterior surfaces of the casingsections 168 have recess configurations 170 thereon (corresponding tothe recess configurations 44 in the casing sections 24 and 26) providingthe exterior of the casing section 168 with a pair of clearance recesses170.2 and with slots 170.5 forming a pair of detent abutments 170.7corresponding to similar features on the exterior of the casing sections24 and 26. A pair of metal mounting clips 172 are disposed on thehousing of the breaker 166 to fit into the recess configurations 170 onthe casing section 168 and into recess configurations 44 on the casingsections 24 and 26, the clips each having a top sheet portion 172.1 witha cam slot 172.2 therein, having a plurality of detent portions 172.3,and having a pair of guide portions 172.4 corresponding to similarfeatures on the previously described mounting clip 46, whereby the edgesof the cam slot 172.2 engage the clamping cam surfaces of the casingsections 24 and 26 and shown in FIG. 22 for holding the casing sections24, 26 and 168 together to form the housing for the circuit breaker 166,whereby each of the detent portions 172.3 fit over respective pairs ofthe detent abutments 44.6 or 170.7 on the casing sections, and wherebylocking tabs on the guide portions 172.4 of the clips fit into lockingslots in the casing sections 24 and 26 for securing the clips 172 on thebreaker housing. In this arrangement no metal rivets such as might causearcing or breakdown between poles extend through the housing sections.The clips 172 are each preferably provided with a plurality of tappedholes 172.5 for use in mounting the multipole circuit breaker 166 on acontrol panel.

Circuit breaker components mounted in the chamber 28 of the circuitbreaker 10 previously described are mounted in each of the chambers 28of the circuit breaker 166 as shown in FIGS. 24-26 so that each pole ofthe circuit breaker is adapted to function as does the circuit breaker10.

In accordance with this invention, the circuit breaker mechanisms in thevarious housing chambers 28 are coupled together so that all poles ofthe multipole breaker are adapted to be manually opened or manuallyclosed at the same time and so that, when one pole of the circuitbreaker open automatically in response to an overload current in thatpole, the other poles of the multipole breaker are also opened promptlytherafter. Thus, as is shown in FIG. 23, a handle tie pin 174 is snuglyfitted into the holes 14.9 in the operating handles 14 of the breaker166 and through helical coil springs 176 (only one of which is shown)disposed between adjacent pairs of the handles 14. The tie pinpreferably has a slight taper 174.1 at least at one end and has at leastone peripheral groove 174.2 therein, preferably tapered at each side asshown, which is located so that, when the pin extends between theoperating handles 14 as in FIG. 23, the peripheral groove 174.2 isaligned with a side edge of one of the handles 14. The springs 176 areproportioned to fill the space between each adjacent pair of operatinghandles when the spring is substantially fully compressed to itsshortest length whereby the springs serve to space the adjacent handlesfrom each other. At least one of the springs also has a convolution176.1 at one end which is of lesser diameter than the other springconvolutions. Preferably for example, one end of the convolution is bentto have a chord configuration. This convolution is located to fit withinthe peripheral groove 174.2 in the tie pin when the tie pin is in theposition shown in FIG. 23, thereby to retain the tie pin in thatposition. In this arrangement, the operating handles of the multipolecircuit breaker 166 are easily coupled together by inserting the taperedpin end through the handle openings 14.9 and alternately through springs176 in sequence until the spring convolution 176.2 snaps into thegrooves 174.1 in the pin. This assembly of the tie pin is easilyaccomplished by feel and does not require any careful handling. In thisway the pin is retained in the position shown in FIG. 23 and the handlesare securely coupled together for movement together in manually openingand closing the poles of the circuit breaker. However, if uncoupling ofthe handles is desired, the tie pin is merely pushed axially from oneend thereof with a nail-like tool until the spring end 176.1 rides up onthe groove taper and snaps out of the pin groove 174.2, whereupon thepin is then easily slid out of the handle holes 14.9 and out of thespacing spring 176. The purchaser of the circuit breaker is able toremove and then replace the gauging rod easily if this is required formounting the breakers on control panels.

In accordance with this invention, the casing section 168 also has anaperture 168.3 therein providing communication between adjacent housingchambers 28 in the multipole breaker 166. See FIGS. 24-26. A pair ofmultipole actuating members 178 and 180 are then fitted together withinthe aperture 168.3 to mount the actuating members 178 and 180 forpivotal movement within respective adjacent chambers 28. That is, theactuator member 178 has a splined bushing part 178.1 extending into theaperture 168.3 to be coupled in closely fitted engagement with acorrespondingly splined bushing part 180.1 of the other actuator member.Each actuator member also has an arm 178.2 and 180.2 extending from thebushing, the arms each having an abutment 178.3 defining a cam surface178.4 and 180.4. The actuator member 178 has a spring stop abutment178.5 on its arm adjacent the bushing part and has a shaft 178.6extending from the actuator to rest in grooves 178.7 on top of the arcchute member 70. In this way, engagement of the arc chutes 70 with partsof the actuators 178 and 180 retain the actuators in the aperture 168.3.A spring 182 is fitted over at least one of the actuators such as 178with one spring end 182.1 engaging the adjacent edge wall of the arcchute 70 and with its opposite end 182.2 engaging a stop such as 178.5to bias the actuator members for clockwise movement as viewed in FIGS.24 and 25.

The aperture 168.3 in the casing section is located, and the actuators178 and 180 are proportioned, so that the abutments 178.3 and 180.3 ofthe actuator members are normally biased by the spring 180 intoengagement with side walls of the arc chute member 70, the abutmentshaving sufficient thickness to extend over contact chambers 70.6 and70.7 formed by the arc chutes in the respective chamber 28. Thus, whenone pole of the circuit breaker 166 is closed as illustrated in FIG. 24,the actuator abutment 178.3 overlies part of the movable contact arm 76in that pole. Accordingly, if that pole of the circuit breaker shouldopen in response to an overload current in the pole circuit so that thecontact arm moves to the open circuit position shown in FIG. 25,movement of the arm 76 engages the actuator abutment, rotates theactuator within that pole to the position shown in FIG. 25, and, becausethat actuator is splined to a corresponding actuator 180 in the adjacentpole, rotates the actuator 180 in a similar way. The cam surface 180.4of the other actuator then engages the rod-like lateral extensions 108.8indicated by broken lines in FIGS. 24-26 on the tripping member of thelinkage 18 in the adjacent pole for tripping that linkage to open thecircuit in the adjacent pole. Upon subsequent reclosing of the circuitsof the breaker 166, the actuators 178 and 180 return to the positionsshown in FIG. 24 under bias of the spring 182. Of course, if all polesof the multiple breaker should be subject to simultaneous overloads thebreaker poles may open substantially simultaneously without reliance onthe actuators 178 and 180.

In this arrangement, the multipole circuit breaker is as easily andaccurately assembled as the circuit breaker 10 and incorporates only alimited number of low cost components differing from those used in thebreaker 10. Further, each pole of the breaker 166 includes a calibrationsystem 22 which is readily accessible from the exterior of the pole evenafter the multipole circuit breaker has been fully assembled. Thus thebreaker 166 is adapted to be calibrated after its assembly as a multiplebreaker, whereby more accurate calibration of the breaker poles iseasily accomplished. Further, test openings 42 are accessible in eachpole and the multipole breaker is easily tested after assembly and iseasily disassembled without damage to breaker components if such testingshould indicate that any breaker component is functioning improperly.The breaker 166 is compact and rugged and each pole of the header isconveniently adapted for series, shunt, or relay trip operation, forauxiliary switch operation, or for flux switch type circuit breakerapplication as may be desired.

It should be understood that all of the circuit breaker embodiments asdescribed above are proportioned so that they are readily adaptable forA.C. or D.C. operation, for single pole or multipole operation, for timedelayed or instantaneous operation, for 50, 60or 400 hertz A.C.operation, and for auxiliary switch or flux switch type operation bysimple substitution of magnetic actuation coils, terminals, casingsections or the like. All of the breakers are adapted to be easily andaccurately assembled without requiring performance of time consuming,expensive or critical hand adjustments at assembly. All of the breakersare easily tested and calibrated and are easily dissassembled after suchtesting with full salvageability of all components.

The improved collapsible linkage, double break contact, and auxiliaryswitch system described herein is described and claimed in the commonlyassigned, copending application for patent of Aime J. Grenier, Ser. No.755,514.

(Attorney Docket 15532), filed of even date herewith.

The improved core, clapper and coil mounting and flux switch magneticcircuit system described herein is described and claimed in the commonlyassigned, copending application for patent of Aime J. Grenier, Ser. No.755,515.

(Attorney Docket 15595), filed of even date herewith.

The improved housing and mounting system described herein is describedand claimed in the commonly assigned, copending application for patentof Aime J. Grenier, Ser. No. 755,780. (Attorney Docket 15594), filed ofeven date herewith.

The improved calibration system described herein is described andclaimed in the commonly assigned, copending application for patent ofAime J. Grenier, Ser. No. 755,516.

(Attorney Docket 15592), filed of even date herewith.

It should be understood that although particular embodiments of thisinvention have been described above by way of illustrating theinvention, the invention includes all modifications and equivalents ofthe described embodiments falling within the scope of the appendedclaims.

I claim:
 1. A multipole circuit breaker comprising a plurality ofhousing sections secured together in side-by-side relation for forming aplurality of housing chambers between respective pairs of the sections;and, in each chamber, fixed contact means, movable contact means movablebetween a position engaging the fixed contact means for closing acircuit and a position spaced from the fixed contact means for openingsaid circuit, means biasing the movable contact means to said opencircuit position, an operating handle extending from the chamber to bemanually moved between corresponding open and closed circuit positions,linkage means connecting the operating handle to the movable contactmeans, said linkage means having a tripping member pivotally movablethereon between a first position permitting the movable contact means tobe moved between said open and closed circuit positions in response tomanual movement of the operating handle and a second position permittingthe movable contact means to move to said open circuit position inresponse to said biasing means independently of the position of theoperating handle, means responsive to conditions in the breaker circuitfor moving the tripping member to said second position on the occurrenceof selected conditions in said circuit, and at least one multipoleactuator member having a cam portion thereon, said actuator member beingpivotally mounted on a housing section for movement between a first anda second position, said actuator member having said cam portion disposedto be engaged when in in said first position of the actuator member bymovement of said movable contact means to said open circuit position formoving the actuator member to said second position thereof, saidactuator member having said cam portion disposed to engage and move thetripping member from its first position to its second position when saidactuator member is moved into said second position of the actuatormember; said circuit breaker having openings in the housing sectionsextending between each pair of adjacent housing chambers, said circuitbreaker having pairs of said multipole actuators in respective adjacenthousing chambers each having a splined shaft extending into one of saidopenings and secured in splined engagement with corresponding shaftportion of the other actuator member of said pair in the adjacenthousing chamber for mounting the actuator member for said pivotalmovement and for connecting the members together for common movementwith each other; whereby movement of the movable contact means in onehousing chamber to open circuit position on the occurrence of saidselected circuit conditions initiates pivotal movement of at least onepair of said multipole actuator members to said second positions of themembers for moving the tripping member in an adjacent housing chamber toopen the circuit in said adjacent housing chamber as said actuatormembers are moved into said second positions of the members.
 2. Amultipole circuit breaker as set forth in claim 1 having said actuatormembers formed of a dielectric material, said members having plateportions of the multipole actuator members fitted over said openings andslidably engaged with said housing sections during pivotal movement ofthe multipole actuators for sealing said openings, and having said camportions extending from respective plate portions to engage said movablecontact means and said tripping member.
 3. A multipole circuit breakeras set forth in claim 2 having spring means biasing said multipoleactuator members away from said tripping members.
 4. A multipole circuitbreaker comprising a plurality of housing sections secured together inside-by-side relation for forming a plurality of housing chambersbetween respective pairs of the sections; and, in each chamber, fixedcontact means, movable contact means movable between a position engagingthe fixed contact means for closing a circuit and a position spaced fromthe fixed contact means for opening said circuit, means biasing themovable contact means to said open circuit position, an operating handleextending from the chamber to be manually moved between correspondingopen and closed circuit positions, linkage means connecting theoperating handle to the movable contact means, said linkage means havinga tripping members pivotally movable thereon between a first positionpermitting the movable contact means to be moved between said open andclosed circuit positions in response to manual movement of the operatinghandle and a second position permitting the movable contact means tomove to said open circuit position in response to said biasing meansindependently of the position of the operating handle, means responsiveto conditions in the breaker circuit for moving the tripping member tosaid second position on the occurrence of selected conditions in saidcircuit, and at least one multipole actuator member pivotally mounted ona housing section to be engaged by movement of said movable contactmeans to said open circuit position to be moved to engage and move thetripping member from its first position to its second position; saidcircuit breaker having pairs of said multipole actuators in respectiveadjacent housing chambers connected together for common movement witheach other, whereby movement of the movable contact means in one housingchamber to open circuit position on the occurrence of said selectedcircuit conditions pivots at least one pair of said multipole actuatormembers for moving the tripping members in an adjacent housing chamberto open the circuit in said adjacent housing chamber; said multipolecircuit breaker having apertures in the respective operating handlesaxially aligned with each other, having a tie-pin extending through saidhandle openings coupling the handles together for common movement witheach other, having at least one peripheral groove extending around thetie-pin at a location between a pair of the operating handles and havingat least one coil spring fitted over the tie-pin extending between saidpair of handles, said coil spring having a convolution thereof of lesserdiameter than other spring convolutions fitted into said pheripheralgroove for detachably retaining the tie-pin in the operating handleopenings.
 5. A multipole circuit breaker as set forth in claim 4 havingsaid groove aligned with an edge of one of said pairs of operatinghandles and having said coil spring convolution of said lesser diameterdisposed at one end of the coil spring.
 6. A multipole circuit breakeras set forth in claim 4 wherein a coil spring is fitted over the tie-pinbetween each adjacent pair of the operating handles, each of said coilsprings having a compessed length corresponding to the separation of theadjacent operating handles for spacing the adjacent operating handlesfrom each other.
 7. In a multiple circuit breaker having a plurality ofoperating handles to be manually moved for opening and closing breakercircuits, said operating handles having respective openings thereinaxially aligned with each other, a tie pin extending through said handleopenings to couple the handles together for common movement, said tiepin having at least one peripheral groove extending around the tie-pinand at least one coil spring fitted over the tie-pin extending between apair of said handles, said coil spring having a convolution of lesserdiameter than other spring convolutions fitted into said peripheralgroove for detachably retaining the tie-pin in the operating handleopenings.
 8. A multipole circuit breaker as set forth in claim 5 whereinsaid groove is aligned with an edge of one of said pair of operatinghandles and said coil spring convolution of lesser diameter is disposedat one end of the coil spring.
 9. A multipole circuit breaker as setforth in claim 7 wherein a coil spring is fitted over the tie-pinbetween each adjacent pair of the operating handles, each of said coilsprings having a compressed length corresponding to the separation ofthe adjacent operating handles for spacing the adjacent operatinghandles from each other while axially positioning the tie-pin relativeto the handles.